1. Technical Field
The present invention relates to inflating devices, and more particularly, to a bi-directional inflating device.
2. Description of Related Art
Tyres of common large trucks are usually disposed in pairs in response to load requirements; that is, there are multiple pairs of an outer tyre and an inner tyre adjacent to each other. Gas nipples of the outer tyre and the inner tyre face inwards and outwards respectively, and a user needs to inflate the outer tyre and the inner tyre by means of a bi-directional inflating device having two inflating fittings.
The conventional bi-directional inflating device has a long rod communicating with a pressure gas source and two inflating fittings combined at an end of the long rod and communicating with the long rod, and the two inflating fittings each are provided with internal threads. The user extends the long rod through a rim of the outer tyre so that the two inflating fittings are located between the inner tyre and the outer tyre. Then, the user sequentially fits the two inflating fittings over the gas nipples of the inner tyre and the outer tyre respectively, and engages the internal threads of the inflating fittings with external threads of the gas nipples respectively to facilitate subsequent inflating operations.
However, both the internal threads of the inflating fittings of the aforesaid inflating device and the external threads of the gas nipples of the tyres have a relatively small depth, so the engagement effect is undesired and the user must continuously apply a force on the long rod during inflation. For example, a push force must be applied continuously when the inner tyre is inflated, and a pull force must be applied continuously when the outer tyre is inflated. In this way, the inflating fittings can be fitted over the gas nipples more stably. This is particularly inconvenient and laborsome in operation, and the inflating device is still liable to gas leakage or disengagement from the gas nipples during inflation.